Extend recommended resume policy to support gRPC

We can close this issue when the `google_cloud_storage::read_resume_policy::Recommended` correctly supports gRPC reads (or at least bidi streaming reads).

## Background

When using JSON the only possible error *after* a read starts is `Error::io`.

When using gRPC we get more error types, including `Error::service()`.

The default read resume policy should handle the additional errors.
